Multi-link SpaceWire Recorder (MSR)

The Multi-link SpaceWire Recorder (MSR) passively records the SpaceWire traffic between devices and subsystems, on up to four links per MSR unit. It monitors packets in both directions on each SpaceWire link, adding time-tags on the start and end of each packet, and sends data to a computer for recording and analysis.

Software is provided to help manage and search the recordings. Multiple MSRs can be synchronized to within 10ns to give uniform time-tags across a system, even if the system has many SpaceWire links and the recordings are being made onto different computers. Low-level SpaceWire errors can be also be recorded and displayed as a waveform trace complete with protocol decode.

Recent successes of the MSR product include:

  • The use of three Multi-link SpaceWire Recorders to monitor a SpaceWire network that contained six processing nodes and two routers. All of the traffic on ten bidirectional SpaceWire links was captured. The results were analysed to show the complete traffic against time, as well as the distribution of latencies for individual links and the effect of blocking in the routers. We could then drill down to inspect particular RMAP protocol interactions and the contents of specific SpaceWire packets.
  • The measurement of the buffer capacity and error-management behaviour of a SpaceWire router, as well as the latency of transmission when its links were clocked at different speeds.
  • The determination of the successful interfacing of an instrument to SpaceWire before the controlling software was configured to complete the communication path.
  • The discovery of a handful of truncated SpaceWire packets in a measurement run of over 17.5 hours, 3.5 million packets and 375Mbytes of recorded data. These were caused when a router disconnected a SpaceWire link just a few tens of nanoseconds before it was due to be used again.
4Links Multi-link SpaceWire Recorder (MSR)

Download the MSR Product Brief (PDF)